Hypoallergenic formulas or compositions which are also referred to as elemental formulas, are characterized in that they contain immunologically unreactive protein hydrolysates or free amino acids. The protein hydrolysates comprise short peptide fragments and/or free amino acids instead of the intact protein found, for example, in cow's milk and soy protein based formulas. These short peptide fragments and free amino acids have been found to be less immunogenic or allergenic than intact proteins.
In addition to the protein hydrolysates and/or free amino acids, most nutritionally balanced elemental or hypoallergenic formulas contain carbohydrates, lipids, vitamins and minerals to provide a nutritionally complete formula. These formulas are utilized for feeding infants, children and adults who have allergies or sensitivities to intact protein and are often medically used in the treatment of cystic fibrosis, chronic diarrhea, small bowel resection, steatorrhea and protein-calorie malnutrition.
One well known problem in the preparation of elemental or hypoallergenic formulas is product instability. Extensive hydrolysis of the protein by acids, or enzymes is necessary to provide the short peptides and amino acids utilized in the formulas to render such formulas hypoallergenic. These extensively digested proteins or free amino acids have undesirable characteristics such as bad taste and loss of capacity to emulsify fat and thereby fail to form physically stable emulsions that do not evidence phase separation.
U.S. Pat. No. 4,414,238 to Schmidl et al. discloses an elemental diet composition comprising carbohydrates, amino acids and/or low molecular weight peptides and lipids. The elemental diet of this patent has a lipid component in the form of an emulsion consisting of lipids, an emulsifier selected from the group consisting of mono- and di-glycerides, and a starch modified with succinic anhydride.
U.S. Pat. No. 4,670,268 to Mahmoud discloses an enteral nutritional hypoallergenic formula which uses a starch modified by octenyl succinic anhydride, which is utilized as the sole lipid emulsifier, to provide a nutritionally well-balanced dietary formula that possesses excellent physical stability.
U.S. Pat. No. 5,411,751 to Crissinger discloses infant formulas which contain no more than subirritant levels of free, long-chain (C.sub.16 -C.sub.22) fatty acids and triglycerides thereof. This patent teaches that digestion products of triglycerides, in particular, long-chain fatty acids and monoglycerides, can damage the intestinal epithelium of infants and thus could mediate the onset of disorders such as necrotizing enterocolitis. This patent does not suggest or disclose a palatable elemental or hypoallergenic medical food that is essentially free of L-glutamic acid and L-aspartic acid.
U.S. Pat. No. 5,234,702 to Katz et al. discloses a powdered nutritional product that uses an antioxidant system to protect the oil component comprising ascorbyl palmitate, beta carotene and/or mixed tocopherols and citrate. The teachings of this patent are incorporated herein by reference.
U.S. Pat. No. Re. 35,233, discloses a method of treating atrophy of skeletal muscle and intestinal mucosa which comprises enterally administering glutamine or a functional derivative thereof in the range of 0.4 to 3.0 g/kg/day.
The nutritional formula according to this invention has been carefully formulated to provide a nutritional product that can be the sole source of nutrition for patients consuming it. To provide effective nutrition to human infants, children and adults, the present invention, in its most specific embodiments, carefully considers the bioavailability of trace and ultratrace minerals and the dietary interactions involving trace elements. Thus, the teachings of Forbes et al, Bioavailability of Trace Mineral Elements, Ann. Rev. Nutr. 1983, 3:213-231 and Mills, Dietary Interactions Involving the Trace Elements, Ann. Rev. Nutr. 1985, 5:173-193, are incorporated herein by reference.
U.S. Pat. Nos. 5,326,569 and 5,550,146 to Acosta et al. disclose a generic powder base, rich in fats, carbohydrates., vitamins, minerals and trace elements which are admixed with specific amino acids to yield several different therapeutic products which are used in the nutritional support of adults and children having various inherited metabolic diseases. These patents do not suggest or disclose the nutritionally complete hypoallergenic formulas of this invention which are essentially free of L-glutamic acid and L-aspartic acid.
The etiology of a number of gastrointestinal conditions has been demonstrated to be caused in some cases by food protein allergens. One such gastrointestinal condition is eosinophilic gastroenteritis. Eosinophilic gastroenteritis is characterized by peripheral eosinophilia, eosinophilic infiltration of the bowel wall, and various gastrointestinal symptoms. In pediatric cases, food antigens are the most common cause of eosinophilic gastroenteritis. Administration of an elemental, hypoallergenic diet may be required for rapid recovery as even extensively hydrolyzed casein-based formulas such as Alimentum.RTM. Protein Hydrolysate Formula With Iron (Ross Products Division, Abbott Laboratories, Columbus, Ohio) contains peptide fragments large enough to evoke an allergic reaction in the most sensitive of allergic individuals.
U.S. Pat. No. 5,492,899 to Masor et al. discloses an enteral nutritional formula containing ribonucleotides at specified levels. The formula of this patent comprises carbohydrates, lipids, proteins, vitamins and minerals and four (4) specified nucleotides at specific levels and ratios. One preferred embodiment of the present invention includes the presence of nucleotides in the elemental hypoallergenic medical food. The teachings of U.S. Pat. No. 5,492,899 are incorporated herein by reference.
U.S. Pat. No. 5,340,603 to Neylan et al. relates to a hypercaloric formula which provides nutritional support for human infants having chronic lung disease. The formula of this patent has a Caloric density of at least 800 kcal per liter of formula and wherein not less than 56% of the total Calories in said formula is derived from fat. In addition, the hypercaloric formula of this reference contains not more than 15% of total Calories derived from a high quality protein source and from about 20 to 27% of total Calories from a carbohydrate source. The formula of this patent also includes m-inositol at a concentration of at least 50 mg per liter of formula.
U.S. Pat. No. 5,411,757 to Buist et al. relates to a balanced, palatable medical diet for treatment of patients with inborn errors of essential amino acid metabolism. The diet of this patent uses L-amino acids at specified weights and ratios. More specifically, this patent discloses a palatable medical diet wherein the protein equivalent of L-amino acids is formed by the acetylation or the esterification of the L-amino acids. In contrast, the present invention uses L-amino acids to supply the amino nitrogen (protein equivalent) except for the replacement of L-asparagine for aspartic acid and L-glutamine for glutamic acid.
A presently available product known as Vivonex.RTM. Pediatric is marketed by the Clinical Products Division of Sandoz Nutrition, Minneapolis, Minn. for the gastrointestinally impaired child. The Vivonex.RTM. Pediatric contains 100% free amino acids and has an osmolality at standard dilution of 1 kcal/ml of 490 mOsm/kg H.sub.2 O. This product derives 25% of total Calories from fat with 68% of those Calories from medium chain triglycerides.
Neocate.RTM. One+ marketed by Scientific Hospital Supplies, Inc. (SHS) North America, Gaithersburg, Md., is a pediatric elemental nutritional that is marketed in liquid and powdered forms and is designed for children over one year of age. This liquid product contains 100% of its amino nitrogen in the form of free L-amino acids and has an osmolality at standard dilution (100 kcal/100 ml) of 835 mOsm/kg H.sub.2 O. Neocate.RTM. One+ powder (unflavored), when mixed to yield 100 kcal/100 mL, has an osmolality of 610 mOsm/kg H.sub.2 O. These products contain 3.5 grams of fat per 100 mL at a Caloric density of 100 kcal/100 mL. Neocate.RTM., also marketed by SHS in the U.K., Scandanavia and the USA, uses maltodextrin as the carbohydrate source, contains 11.4% of Calories from free L-amino acids and 44.3% of Calories from fat wherein the fat is a mixture of refined lard, peanut oil and coconut oil.
In general, the prior art elemental or hypoallergenic formulas suffer from poor taste (organoleptic properties), high osmolarity and low Caloric density. In contrast, the present invention has acceptable organoleptic properties thereby facilitating oral consumption by the patient which also increases patient compliance with diet restrictions. The improved organoleptic properties are accomplished in part, by essentially excluding L-glutamic acid and L-aspartic acid from the formula and replacing them with L-glutamine and L-asparagine monohydrate. Further, the present invention is differentiated from the prior art in that it contains a higher Caloric content from fat which assists in improving organoleptic properties; reduces osmolality and increases overall Caloric density. Further, the specific fat blend of the invention provides a balance of the essential fatty acids linoleic and .alpha.-linolenic, in a readily absorbable form.